[Supernaut]

I just bought an 85 T/A. I Drove it 600 miles back from Portland OR To Montana. The car has no power at over 3500 RPM. If you happen to be in overdrive when you stomp on it, the car bucks and vibrates, but doesn't really go much faster. It has the 305 LG4 motor in it. 700R4 trans, the motor and trans were supposed to have been rebuilt 1500 miles ago, but on the same token the car had only been driven 1200 miles in the last seven years. I changed the thermostat becaue the temperature guage was reading 160 max, and the catalytic converter was glowing orange one morning when it was warming up. I put in a 180 degree stat, but when we ran the car again the temp guage was still reading 160. Item of note: When the thermostat was being changed we noticed that the sending unit in the thermostat housing was not seated all the way and had some crusty VERY hard white goop on it, so we pulled out the sensor and cleaned it up with a wire brush but it still wouldn't go all the way in, there are about 1/4 of an inch of threads left. Is this a problem, and where do I go from here. STUCK! Thanks for any suggestions.